10 Dollars Brunelleschi Dome - 9 of 9

The ninth and final piece in Niue's architectural domed-structures series, this coin closed out a set built around some of history's most structurally ambitious buildings. Brunelleschi solved the problem of spanning Florence Cathedral's crossing in 1420 without centering — the conventional timber falsework that would have been required simply didn't exist in sufficient quantity in Tuscany at the time. His double-shell brick herringbone technique, drawn partly from Roman concrete construction he studied firsthand in Rome, produced a dome that remained the largest in the world for over a century.